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authorVincent Ambo <mail@tazj.in>2021-12-13T22·51+0300
committerVincent Ambo <mail@tazj.in>2021-12-13T23·15+0300
commit019f8fd2113df4c5247c3969c60fd4f0e08f91f7 (patch)
tree76a857f61aa88f62a30e854651e8439db77fd0ea /users/wpcarro/scratch/deepmind/part_two/find-rotation-point.ts
parent464bbcb15c09813172c79820bcf526bb10cf4208 (diff)
parent6123e976928ca3d8d93f0b2006b10b5f659eb74d (diff)
subtree(users/wpcarro): docking briefcase at '24f5a642' r/3226
git-subtree-dir: users/wpcarro
git-subtree-mainline: 464bbcb15c09813172c79820bcf526bb10cf4208
git-subtree-split: 24f5a642af3aa1627bbff977f0a101907a02c69f
Change-Id: I6105b3762b79126b3488359c95978cadb3efa789
Diffstat (limited to 'users/wpcarro/scratch/deepmind/part_two/find-rotation-point.ts')
-rw-r--r--users/wpcarro/scratch/deepmind/part_two/find-rotation-point.ts68
1 files changed, 68 insertions, 0 deletions
diff --git a/users/wpcarro/scratch/deepmind/part_two/find-rotation-point.ts b/users/wpcarro/scratch/deepmind/part_two/find-rotation-point.ts
new file mode 100644
index 000000000000..7bf1a484454d
--- /dev/null
+++ b/users/wpcarro/scratch/deepmind/part_two/find-rotation-point.ts
@@ -0,0 +1,68 @@
+function findRotationPoint(xs: Array<string>): number {
+  // Find the rotation point in the vector.
+  let beg = 0;
+  let end = xs.length - 1;
+
+  while (beg != end) {
+    let mid = beg + Math.floor((end - beg) / 2);
+
+    if (beg === mid) {
+      return xs[beg] < xs[end] ? beg : end;
+    }
+
+    if (xs[end] <= xs[mid]) {
+      beg = mid;
+      end = end;
+    } else {
+      beg = beg;
+      end = mid;
+    }
+  }
+
+  return beg;
+}
+
+// Tests
+let desc;
+let actual;
+let expected;
+
+desc = "small array one";
+actual = findRotationPoint(["cape", "cake"]);
+expected = 1;
+assertEquals(actual, expected, desc);
+
+desc = "small array two";
+actual = findRotationPoint(["cake", "cape"]);
+expected = 0;
+assertEquals(actual, expected, desc);
+
+desc = "medium array";
+actual = findRotationPoint(["grape", "orange", "plum", "radish", "apple"]);
+expected = 4;
+assertEquals(actual, expected, desc);
+
+desc = "large array";
+actual = findRotationPoint([
+  "ptolemaic",
+  "retrograde",
+  "supplant",
+  "undulate",
+  "xenoepist",
+  "asymptote",
+  "babka",
+  "banoffee",
+  "engender",
+  "karpatka",
+  "othellolagkage"
+]);
+expected = 5;
+assertEquals(actual, expected, desc);
+
+function assertEquals(a, b, desc) {
+  if (a === b) {
+    console.log(`${desc} ... PASS`);
+  } else {
+    console.log(`${desc} ... FAIL: ${a} != ${b}`);
+  }
+}